Elastic and thermoelastic constants of nepheline

Bonczar, L. J.; Barsch, G. R.

doi:10.1063/1.321457

Cited by 56 publications

(2 citation statements)

References 8 publications

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“…The anomalous elastic constant temperature behaviour in &-quartz is probably associated with the untilting of the mutually rotated, rigid Si04 tetrahedral groups as the crystal is heated towards the a-@phase transition at 573 "C. Such anomalous behaviour has also been observed in other materials where the structure consists of rigid, mutually rotated groups which untilt as the temperature is increased e.g. Te02 (Leciejewicz 1961, Ohmachi andUchida 1972) and nepheline (Bonczar and Barsch 1975). However, an examination of the materials which possess anomalous elastic constant temperature behaviour shows that this type of crystal structure is not the only favourable one.…”

Section: Introductionmentioning

confidence: 77%

The electromechanical and SAW properties of proustite and pyrargyrite

O’Hara¹,

Shorrocks²,

Whatmore³

et al. 1982

J. Phys. D: Appl. Phys.

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The elastic, piezoelectric and dielectric properties of proustite (Ag3AsS3) and pyrargyrite (Ag3SbS3) and their first-order temperature coefficients have been determined at room temperature. A full set of the relevant coefficients has been derived for proustite and these have been used for the prediction of the material's SAW properties as a function of temperature. A more limited set of coefficients has been derived for pyrargyrite and these are compared with the coefficients for proustite. Both materials show markedly anomalous elastic constant behaviour as a function of temperature and have properties which appear to be promising for low velocity SAW applications.

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Section: Introductionmentioning

confidence: 77%

The electromechanical and SAW properties of proustite and pyrargyrite

O’Hara¹,

Shorrocks²,

Whatmore³

et al. 1982

J. Phys. D: Appl. Phys.

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“…2). The adiabatic bulk modulus obtained by Bonczar and Barsch (1975) by in situ single-crystal ultrasonic measurements [B 0 = 4.9(7) × 10 11 dyn/cm 2 ≈ 49 (7) (72) 0.0230(9) † Notes: Estimated standard deviations are in parentheses. For each site, the values from top to bottom correspond to the refi nement at 0.0001 (in air), 0.0001 (with crystal in the DAC), 1.967(5), 4.130(5), 6.108(6), 7.462(7), and 0.0001 GPa (with crystal in air, after decompression).…”

Section: Satellite Intensitiesmentioning

confidence: 99%

Elastic behavior and pressure-induced structural evolution of nepheline: Implications for the nature of the modulated superstructure

Gatta

Angel

2007

American Mineralogist

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The elastic behavior and the pressure-induced structural evolution of a natural nepheline (K 0.54 Na 3.24 Ca 0.03 Al 4 Si 4 O 16 ) were investigated by in-situ single-crystal X-ray diffraction up to 7.5 GPa with a diamond anvil cell under hydrostatic conditions. As observed in previous studies, at room conditions the diffraction pattern of nepheline includes satellite refl ections, whereas the structure refi nement to the Bragg refl ections confi rms that the O1 site is displaced from the triad at (2/3, 1/3, z). The refl ection conditions confi rm that the space group of the average structure of nepheline remains as P6 3 throughout the pressure range investigated, and no signifi cant compression of the T-O bonds was measured up to 7.5 GPa. As pressure was increased to around 1 GPa the integrated intensities of the satellites decreased slightly, and at 1.8 GPa no signifi cant intensity of the satellites was detected. Over the same pressure range the O1 site moved toward the triad and thus the tilts of the T1 and T2 tetrahedra decreased. The presence of the subsidiary non-Bragg refl ections is therefore related to the split of the O1 site. When the satellites disappear at pressures above 2 GPa, the O1 site is on the triad at (2/3, 1/3, z), corresponding to a straight T1-O1-T2 bond. Below 2 GPa the structure responds to increased pressure by tilting of all four tetrahedra and above 2 GPa by tilting of the T3 and T4 tetrahedra alone. The change in compression mechanism arising from the changes in the O1 position is associated with changes in the compression of the unit-cell axes and the unit-cell volume. The volume can be described by fourth-order Birch-Murnaghan equation-of-state with parameters V 0 = 723.57(4) Å 3 , K T0 = 47.32(26) GPa, K' = 2.77(24), and K'' = 0.758(79) GPa -1 . The elastic behavior along the a-and c-axis can be described with a "linearized" fourth-order Birch-Murnaghan equations-of-state, with the following refi ned parameters: a 0 = 9.9911(2) Å, K T0 (a) = 43.1(3) GPa, K'(a) = 2.5(3), and K''(a) = 0.68(8) GPa -1 for the a-axis and c 0 = 8.3700(1) Å, K T0 (c) = 58.6(3) GPa, K'(c) = 4.0(3), and K''(c) = 0.85(11) GPa -1 for the c-axis. The pressure-induced structural evolution in nepheline up to 7.5 GPa appears to be completely reversible. The recovery of the modulation upon complete pressure release points to the framework of nepheline having an instability corresponding to a rigid-unit mode with a wave vector corresponding to the observed positions of the satellite refl ections.

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Mg - Zr

Every¹,

McCurdy²

Second and Higher Order Elastic Constants

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Elastic and thermoelastic constants of nepheline

Cited by 56 publications

References 8 publications

The electromechanical and SAW properties of proustite and pyrargyrite

The electromechanical and SAW properties of proustite and pyrargyrite

Elastic behavior and pressure-induced structural evolution of nepheline: Implications for the nature of the modulated superstructure

Mg - Zr

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